Method for transfer of a thin layer of silicon

ABSTRACT

A method for preparing semiconductor on insulator structures comprises transferring a thin layer of silicon from a donor substrate onto a handle substrate.

CROSS REFERENCE TO RELATED APPLICATION(S)

This application is a continuation of U.S. application Ser. No.16/420,637, which was filed May 23, 2019, the disclosure of which isincorporated by reference as if set forth in its entirety. U.S.application Ser. No. 16/420,637 claims the benefit of priority to U.S.provisional application Ser. No. 62/682,228, filed on Jun. 8, 2018, thedisclosure of which is incorporated by reference as if set forth in itsentirety.

FIELD OF THE INVENTION

The present invention generally relates to the field of semiconductorwafer manufacture. More specifically, the present invention relates to amethod of transferring thin silicon layers from a donor substrate to ahandle substrate in the manufacture of silicon-on-insulator structures.

BACKGROUND OF THE INVENTION

Semiconductor wafers are generally prepared from a single crystal ingot(e.g., a silicon ingot) which is trimmed and ground to have one or moreflats or notches for proper orientation of the wafer in subsequentprocedures. The ingot is then sliced into individual wafers. Whilereference will be made herein to semiconductor wafers constructed fromsilicon, other materials may be used to prepare semiconductor wafers,such as germanium, silicon carbide, silicon germanium, gallium arsenide,and other alloys of Group III and Group V elements, such as galliumnitride or indium phosphide, or alloys of Group II and Group VIelements, such as cadmium sulfide or zinc oxide.

Semiconductor wafers (e.g., silicon wafers) may be utilized in thepreparation of composite layer structures. A composite layer structure(e.g., a semiconductor-on-insulator, and more specifically, asilicon-on-insulator (SOI) structure) generally comprises a handle waferor layer, a device layer, and an insulating (i.e., dielectric) film(typically an oxide layer) between the handle layer and the devicelayer. Generally, the device layer is between 0.01 and 20 micrometersthick, such as between 0.05 and 20 micrometers thick. Thick film devicelayers may have a device layer thickness between about 1.5 micrometersand about 20 micrometers. Thin film device layers may have a thicknessbetween about 0.01 micrometer and about 0.20 micrometer. In general,composite layer structures, such as silicon-on-insulator (SOI),silicon-on-sapphire (SOS), and silicon-on-quartz, are produced byplacing two wafers in intimate contact, thereby initiating bonding byvan der Waal's forces, followed by a thermal treatment to strengthen thebond. The anneal may convert the terminal silanol groups to siloxanebonds between the two interfaces, thereby strengthening the bond.

After thermal anneal, the bonded structure undergoes further processingto remove a substantial portion of the donor wafer to achieve layertransfer. For example, wafer thinning techniques, e.g., etching orgrinding, may be used, often referred to as back etch SOI (i.e., BESOI),wherein a silicon wafer is bound to the handle wafer and then slowlyetched away until only a thin layer of silicon on the handle waferremains. See, e.g., U.S. Pat. No. 5,189,500, the disclosure of which isincorporated herein by reference as if set forth in its entirety. Thismethod is time-consuming and costly, wastes one of the substrates andgenerally does not have suitable thickness uniformity for layers thinnerthan a few microns.

Another common method of achieving layer transfer utilizes a hydrogenimplant followed by thermally induced layer splitting. Particles (atomsor ionized atoms, e.g., hydrogen atoms or a combination of hydrogen andhelium atoms) are implanted at a specified depth beneath the frontsurface of the donor wafer. The implanted particles form a cleave planein the donor wafer at the specified depth at which they were implanted.The surface of the donor wafer is cleaned to remove organic compounds orother contaminants, such as boron compounds, deposited on the waferduring the implantation process.

The front surface of the donor wafer is then bonded to a handle wafer toform a bonded wafer through a hydrophilic bonding process. Prior tobonding, the donor wafer and/or handle wafer are activated by exposingthe surfaces of the wafers to plasma containing, for example, oxygen ornitrogen. Exposure to the plasma modifies the structure of the surfacesin a process often referred to as surface activation, which activationprocess renders the surfaces of one or both of the donor water andhandle wafer hydrophilic. The surfaces of the wafers can be additionallychemically activated by a wet treatment, such as an SC1 clean orhydrofluoric acid. The wet treatment and the plasma activation may occurin either order, or the wafers may be subjected to only one treatment.The wafers are then pressed together, and a bond is formed therebetween. This bond is relatively weak, due to van der Waal's forces, andmust be strengthened before further processing can occur.

In some processes, the hydrophilic bond between the donor wafer andhandle wafer (i.e., a bonded wafer) is strengthened by heating orannealing the bonded wafer pair. In some processes, wafer bonding mayoccur at low temperatures, such as between approximately 300° C. and500° C. In some processes, wafer bonding may occur at high temperatures,such as between approximately 800° C. and 1100° C. The elevatedtemperatures cause the formation of covalent bonds between the adjoiningsurfaces of the donor wafer and the handle wafer, thus solidifying thebond between the donor wafer and the handle wafer. Concurrently with theheating or annealing of the bonded wafer, the particles earlierimplanted in the donor wafer weaken the cleave plane.

A portion of the donor wafer is then separated (i.e., cleaved) along thecleave plane from the bonded wafer to form the SOI wafer. Cleaving maybe carried out by placing the bonded wafer in a fixture in whichmechanical force is applied perpendicular to the opposing sides of thebonded wafer in order to pull a portion of the donor wafer apart fromthe bonded wafer. According to some methods, suction cups are utilizedto apply the mechanical force. The separation of the portion of thedonor wafer is initiated by applying a mechanical wedge at the edge ofthe bonded wafer at the cleave plane in order to initiate propagation ofa crack along the cleave plane. The mechanical force applied by thesuction cups then pulls the portion of the donor wafer from the bondedwafer, thus forming an SOI wafer.

According to other methods, the bonded pair may instead be subjected toan elevated temperature over a period of time to separate the portion ofthe donor wafer from the bonded wafer. Exposure to the elevatedtemperature causes initiation and propagation of cracks along the cleaveplane, thus separating a portion of the donor wafer. The crack forms dueto the formation of voids from the implanted ions, which grow by Ostwaldripening. The voids are filled with hydrogen and helium. The voidsbecome platelets. The pressurized gases in the platelets propagatemicro-cavities and micro-cracks, which weaken the silicon on the implantplane. If the anneal is stopped at the proper time, the weakened bondedwafer may be cleaved by a mechanical process. However, if the thermaltreatment is continued for a longer duration and/or at a highertemperature, the micro-crack propagation reaches the level where allcracks merge along the cleave plane, thus separating a portion of thedonor wafer. This method allows for better uniformity of the transferredlayer and allows recycle of the donor wafer, but typically requiresheating the implanted and bonded pair to temperatures approaching 500°C.

SUMMARY OF THE INVENTION

The present invention is directed to a method of transferring a siliconlayer from a single crystal silicon donor substrate to a handlesubstrate, the method comprising: (a) implanting H₂ ⁺ ions, H⁺ ions, ora combination of H₂ ⁺ ions and H⁺ ions through a silicon dioxide layerin contact with a front surface of the single crystal silicon donorsubstrate and through the front surface of the single crystal silicondonor substrate, the single crystal silicon donor substrate comprisingtwo major, parallel surfaces one of which is the front surface and oneof which is the back surface, a circumferential edge joining the frontsurface and the back surface, a central plane between the front surfaceand the back surface, a central axis perpendicular to the front surface,and a bulk region between the front surface and the back surface; (b)implanting He⁺ ions through the silicon dioxide layer in contact withthe front surface of a single crystal silicon donor substrate andthrough the front surface of the single crystal silicon donor substrate;(c) annealing the ion implanted single crystal silicon donor substrateat a temperature and for a duration sufficient to form a damage layer inthe single crystal silicon donor substrate; (d) bonding the silicondioxide layer in contact with the front surface of the single crystalsilicon donor substrate to a dielectric layer in contact with the handlesubstrate to thereby prepare the multilayer substrate; (e) annealing themultilayer substrate; and (f) cleaving the annealed multilayer substrateat the damage layer in the single crystal silicon donor substrate tothereby transfer the silicon layer having a thickness between about 500Angstroms and about 2500 Angstroms from the single crystal silicon donorsubstrate to the handle substrate.

Other objects and features will be in part apparent and in part pointedout hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A through 1F depict a process flow according to some embodimentsof the present invention.

FIG. 2 is a graph depicting SRIM calculated depth profiles of H⁺ and He⁺ions implanted at 16 Kev and 22 kev respectively. These data wereobtained according to the method of Example 1.

FIG. 3 is a graph depicting post cleave thickness variation ranges (●)of the transferred silicon device layer for various H₂ ⁺ doses.

FIG. 4 is a graph depicting SRIM calculated depth profiles of H⁺ and He⁺ions implanted at 8 Kev and 11 kev respectively. These data wereobtained according to the method of Example 2.

DETAILED DESCRIPTION OF THE EMBODIMENT(S) OF THE INVENTION

A Fully Depleted Silicon-on-Insulator (FD-SOI) structure relies on anultra-thin layer of silicon over a Buried Oxide layer (BOX). The buriedoxide layer may be of conventional thickness (on the order of 100 to 200nanometers) or it may also be ultra-thin, for example, between 10 to 25nm. The very thin silicon layer enables the silicon under the transistorgate (the body of the transistor) of a CMOS device to be fully depletedof charges. The present invention is therefore directed to a method oftransferring very thin silicon layers from a donor substrate to a handlesubstrate.

According to the present invention, a method is provided for preparing asemiconductor-on-insulator composite structure (SOI, e.g., asilicon-on-insulator composite structure) having a relatively thinsilicon device layer. In some embodiments, the SOI structure furthercomprises a relatively thin dielectric layer, e.g., a buried oxidelayer. In some embodiments, the present invention is therefore directedto a method of transferring thin silicon layers of thickness betweenabout 500 angstroms and about 2500 angstroms from a donor substrate ontoa handle substrate. According to some embodiments of the presentinvention, Hydrogen (H₂ ⁺ and/or H⁺) ions and Helium (He⁺) ions areco-implanted into the donor substrate at low ion energies. Annealing theco-implanted donor substrate forms a damage layer in the donorsubstrate. The depth of the damage layer determines the thickness of thelayer of silicon transferred onto the handle substrate.

In order to achieve thin layer transfer, the implantation energies ofthe gaseous ions are kept low, especially when the oxide layer thicknesson the donor wafer is also thin (e.g., a few hundred Angstroms).Transfer of a thin silicon device layer enables preparation offully-depleted SOI structures (FD-SOI). Low power, high performance CMOSapplications based on FD-SOI require the thickness of the silicon devicelayer and the thickness of the buried oxide layer be limited. Thinlayers may be transferred by limiting the beam energy during ionimplantation. Further, according to some embodiments, the manufacturingcosts of production are further reduced by reducing the implantationdosages.

I. Semiconductor Donor Substrate and Semiconductor Handle Substrate

The substrates for use in the present invention include a semiconductordonor substrate, e.g., a single crystal semiconductor donor wafer, and asemiconductor handle substrate, e.g., a single crystal semiconductorhandle wafer. The semiconductor device layer in asemiconductor-on-insulator composite structure is derived from thesemiconductor donor substrate.

FIGS. 1A through 1F depict a process flow according to some embodimentsof the present invention. With reference to FIG. 1A, an exemplary,non-limiting semiconductor donor substrate 100, e.g. a single crystalsemiconductor donor wafer, is depicted. In general, the single crystalsemiconductor donor substrate 100 comprises two major, generallyparallel surfaces. One of the parallel surfaces is a front surface 102of the single crystal semiconductor donor substrate 100, and the otherparallel surface is a back surface 104 of the single crystalsemiconductor donor substrate 100. The single crystal semiconductordonor substrate 100 comprises a circumferential edge 106 joining thefront and back surfaces 102, 104. The single crystal semiconductor donorsubstrate 100 comprise a central axis 108 perpendicular to the twomajor, generally parallel surfaces 102, 104 and also perpendicular to acentral plane 110 defined by the points midway between the front andback surfaces 102, 104. The single crystal semiconductor donor substrate100 comprises a bulk region between the two major, generally parallelsurfaces 102, 104. Since semiconductor wafers, e.g., silicon wafers,typically have some total thickness variation (TTV), warp, and bow, themidpoints defining the central plane 110 between every point on thefront surface 102 and every point on the back surface 104 may notprecisely fall within a plane. As a practical matter, however, the TTV,warp, and bow are typically so slight that to a close approximation themidpoints can be said to fall within an imaginary central plane 110which is approximately equidistant between the front and back surfaces102, 104.

Prior to any operation as described herein, the front surface 102 andthe back surface 104 of the single crystal semiconductor donor substrate100 may be substantially identical. A surface is referred to as a “frontsurface” or a “back surface” merely for convenience and generally todistinguish the surface upon which the operations of method of thepresent invention are performed. In the context of the presentinvention, a “front surface” of a single crystal semiconductor donorsubstrate 100 refers to the major surface of the substrate through whichions are implanted. The front surface becomes an interior surface of thebonded structure. Accordingly, a “back surface” of a single crystalsemiconductor donor substrate 100 refers to the major surface thatbecomes an exterior surface of the bonded structure. Similarly, a “frontsurface” of a handle substrate refers to the major surface of the handlesubstrate that becomes an interior surface of the bonded structure, anda “back surface” of a handle substrate refers to the major surface thatbecomes an exterior surface of the bonded structure. Upon completion ofconventional bonding and cleaving steps, the single crystalsemiconductor donor substrate forms the semiconductor device layer ofthe semiconductor-on-insulator (e.g., silicon-on-insulator) compositestructure.

The handle substrate and the single crystal semiconductor donorsubstrate may be single crystal semiconductor wafers. In preferredembodiments, the semiconductor wafers comprise a material selected fromthe group consisting of silicon, silicon carbide, silicon germanium,gallium arsenide, gallium nitride, indium phosphide, indium galliumarsenide, germanium, and combinations thereof. Handle wafers mayadditionally comprise sapphire, quartz, or glass. The single crystalsemiconductor wafers, e.g., the single crystal silicon handle wafer andsingle crystal silicon donor wafer, of the present invention typicallyhave a nominal diameter of at least about 150 mm, at least about 200 mm,at least about 300 mm, or at least about 450 mm. Wafer thicknesses mayvary from between about 100 micrometers and about 5000 micrometers, suchas between about 100 micrometers and about 1500 micrometers, such asbetween about 250 micrometers to about 1500 micrometers, such as betweenabout 300 micrometers and about 1000 micrometers, suitably within therange of about 500 micrometers to about 1000 micrometers. In somespecific embodiments, the wafer thickness may be about 725 micrometers.In some embodiments, the wafer thickness may be about 775 micrometers.

In particularly preferred embodiments, the single crystal semiconductorwafers comprise single crystal silicon wafers which have been slicedfrom a single crystal ingot grown in accordance with conventionalCzochralski crystal growing methods or float zone growing methods. Suchmethods, as well as standard silicon slicing, lapping, etching, andpolishing techniques are disclosed, for example, in F. Shimura,Semiconductor Silicon Crystal Technology, Academic Press, 1989, andSilicon Chemical Etching, (J. Grabmaier ed.) Springer-Verlag, N.Y., 1982(incorporated herein by reference). Preferably, the wafers are polishedand cleaned by standard methods known to those skilled in the art. See,for example, W.C. O'Mara et al., Handbook of Semiconductor SiliconTechnology, Noyes Publications. If desired, the wafers can be cleaned,for example, in a standard SC1 (5 parts water:1 part aqueous ammoniumhydroxide (29% by weight):1 part aqueous hydrogen peroxide (30% byweight))/SC2 solution (6 parts water:1 part aqueous hydrochloric acid(37% by weight):1 part aqueous hydrogen peroxide (30% by weight)). Insome embodiments, the single crystal silicon wafers of the presentinvention are single crystal silicon wafers which have been sliced froma single crystal ingot grown in accordance with conventional Czochralski(“Cz”) crystal growing methods, typically having a nominal diameter ofat least about 150 mm, at least about 200 mm, at least about 300 mm, orat least about 450 mm. Preferably, both the single crystal siliconhandle wafer and the single crystal silicon donor wafer havemirror-polished front surface finishes that are free from surfacedefects, such as scratches, large particles, etc. Wafer thickness mayvary from about 250 micrometers to about 1500 micrometers, such asbetween about 300 micrometers and about 1000 micrometers, suitablywithin the range of about 500 micrometers to about 1000 micrometers. Insome specific embodiments, the wafer thickness may be between about 725micrometers and about 800 micrometers, such as between about 750micrometers and about 800 micrometers. In some embodiments, the waferthickness may be about 725 micrometers. In some embodiments, the waferthickness may be about 775 micrometers.

In some embodiments, the single crystal semiconductor wafers, i.e.,single crystal semiconductor handle wafer and single crystalsemiconductor donor wafer, comprise interstitial oxygen inconcentrations that are generally achieved by the Czochralski-growthmethod. In some embodiments, the single crystal semiconductor waferscomprise oxygen in a concentration between about 4 PPMA and about 18PPMA. In some embodiments, the semiconductor wafers comprise oxygen in aconcentration between about 10 PPMA and about 35 PPMA. In someembodiments, the single crystal silicon wafer comprises oxygen in aconcentration of no greater than about 10 PPMA. Interstitial oxygen maybe measured according to SEMI MF 1188-1105.

The single crystal semiconductor donor substrate 100 and the handlesubstrate may have any resistivity obtainable by the Czochralski orfloat zone methods. Accordingly, the resistivity of the single crystalsemiconductor donor substrate 100 and the handle substrate is based onthe requirements of the end use/application of the structure of thepresent invention. The resistivity may therefore vary from milliohm orless to megaohm or more. In some embodiments, the single crystalsemiconductor donor substrate 100 is undoped. In some embodiments, thehandle substrate 100 is undoped. In some embodiments, the single crystalsemiconductor donor substrate 100 comprises a p-type or an n-typedopant. In some embodiments, the handle substrate 100 comprises a p-typeor an n-type dopant. Suitable dopants include boron (p type), gallium (ptype), aluminum (p type), indium (p type), phosphorus (n type), antimony(n type), and arsenic (n type). The dopant concentration is selectedbased on the desired resistivity of the single crystal semiconductordonor substrate.

In some embodiments, the single crystal semiconductor donor substrate100 has a relatively low minimum bulk resistivity, such as below about100 ohm-cm, below about 50 ohm-cm, below about 1 ohm-cm, below about 0.1ohm-cm, or even below about 0.01 ohm-cm. In some embodiments, the singlecrystal semiconductor donor substrate 100 has a relatively low minimumbulk resistivity, such as below about 100 ohm-cm, or between about 1ohm-cm and about 100 ohm-cm. Low resistivity wafers may compriseelectrically active dopants, such as boron (p type), gallium (p type),aluminum (p type), indium (p type), phosphorus (n type), antimony (ntype), and arsenic (n type).

In some embodiments, the single crystal semiconductor donor substrate100 has a relatively high minimum bulk resistivity. High resistivitywafers are generally sliced from single crystal ingots grown by theCzochralski method or float zone method. High resistivity wafers maycomprise electrically active dopants, such as boron (p type), gallium (ptype), aluminum (p type), indium (p type), phosphorus (n type), antimony(n type), and arsenic (n type), in generally very low concentrations.Cz-grown silicon wafers may be subjected to a thermal anneal at atemperature ranging from about 600° C. to about 1000° C. in order toannihilate thermal donors caused by oxygen that are incorporated duringcrystal growth. In some embodiments, the single crystal semiconductorhandle wafer has a minimum bulk resistivity of at least 100 Ohm-cm, oreven at least about 500 Ohm-cm, such as between about 100 Ohm-cm andabout 100,000 Ohm-cm, or between about 500 Ohm-cm and about 100,000Ohm-cm, or between about 1000 Ohm-cm and about 100,000 Ohm-cm, orbetween about 500 Ohm-cm and about 10,000 Ohm-cm, or between about 750Ohm-cm and about 10,000 Ohm-cm, between about 1000 Ohm-cm and about10,000 Ohm-cm, between about 1000 Ohm-cm and about 6000 ohm-cm, betweenabout 2000 Ohm-cm and about 10,000 Ohm-cm, between about 3000 Ohm-cm andabout 10,000 Ohm-cm, or between about 3000 Ohm-cm and about 5,000Ohm-cm. In some preferred embodiments, the single crystal semiconductorhandle wafer has a bulk resistivity between about 1000 Ohm-cm and about6,000 Ohm-cm. Methods for preparing high resistivity wafers are known inthe art, and such high resistivity wafers may be obtained fromcommercial suppliers, such as SunEdison Semiconductor Ltd. (St. Peters,Mo.; formerly MEMC Electronic Materials, Inc.).

The single crystal semiconductor donor substrate 100 may comprise singlecrystal silicon. The single crystal semiconductor donor substrate 100may have any of (100), (110), or (111) crystal orientation, and thechoice of crystal orientation may be dictated by the end use of thestructure.

Optionally, the front surface 102, the back surface 104, or bothsurfaces of the single crystal semiconductor donor substrate 100 may beoxidized according to methods known in the art. Oxidation may beaccomplished by means known in the art, such as thermal oxidation (inwhich some portion of the deposited semiconductor material film will beconsumed), CVD oxide deposition, or by exposure to a standard cleaningsolution, such as an SC1/SC2 cleaning solution. The single crystalsemiconductor donor substrate 100 may be thermally oxidized in a furnacesuch as an ASM A400 or ASM A400XT. The temperature may range from 750°C. to 1100° C., such as between about 800° C. and about 1200° C., in anoxidizing ambient. The oxidizing ambient atmosphere can be a mixture ofinert gas, such as Ar or N₂, and O₂. The oxygen content may vary from 1to 10 percent, or higher. In some embodiments, the oxidizing ambientatmosphere may be up to 100% (a “dry oxidation”). In some embodiments,the ambient atmosphere may comprises a mixture of inert gas, such as Aror N₂, and oxidizing gases, such as O₂ and water vapor (a “wetoxidation”). In an exemplary embodiment, donor wafers may be loaded intoa vertical furnace, such as an ASM A400 or ASM A400XT. The temperatureis ramped to the oxidizing temperature with a mixture of N₂ and O₂. Atthe desired temperature water vapor is introduced into the gas flow.After desired oxide thickness has been obtained, the water vapor and O₂are turned off and the furnace temperature is reduced and wafers areunloaded from the furnace. In embodiments wherein the single crystalsemiconductor donor substrate 100 is a single crystal silicon donorsubstrate, the oxidation layer 120 comprises silicon dioxide. See FIG.1B. The oxidation layer 120 on the front surface 102, the back surface104, or both may be between about 100 angstroms and about 1000angstroms, such as between about 100 angstroms and about 700 angstroms,or between about 100 angstroms and about 500 angstroms, or between about100 angstroms and about 250 angstroms.

In some embodiments, the oxidation layer 120 is relatively thin, such asbetween about 5 angstroms and about 25 angstroms, such as between about10 angstroms and about 15 angstroms. Thin oxide layers can be obtainedon both sides of a semiconductor wafer by exposure to a standardcleaning solution, such as an SC1/SC2 cleaning solution. In someembodiments, the SC1 solution comprises 5 parts deioinized water, 1 partaqueous NH₄OH (ammonium hydroxide, 29% by weight of NH₃), and 1 part ofaqueous H₂O₂ (hydrogen peroxide, 30%). In some embodiments, the handlewafer may be oxidized by exposure to an aqueous solution comprising anoxidizing agent, such as an SC2 solution. In some embodiments, the SC2solution comprises 5 parts deioinized water, 1 part aqueous HCl(hydrochloric acid, 39% by weight), and 1 part of aqueous H₂O₂ (hydrogenperoxide, 30%).

II. Ion Implantation

Ion implantation may be carried out in a commercially availableinstrument, such as an Applied Materials Quantum II, a Quantum LEAP, ora Quantum X. According to some embodiments, the implanted ions include acombination of H⁺ and/or H₂ ⁺ ions and He⁺ ions. The H⁺ and/or H₂ ⁺ ionsmay be implanted before the He⁺ ions implanted, after the He⁺ ionsimplanted, or the H⁺ and/or H₂ ⁺ ions may be implanted simultaneouslywith the He⁺ ions. Ion implantation is carried out at a density andduration sufficient to form a damage layer in the semiconductor donorsubstrate. With reference to FIG. 1C, ion implantation occurs throughthe oxidation layer 120 and the front surface 102 of the single crystalsemiconductor donor substrate 100, such that the single crystalsemiconductor donor substrate 100 comprises H⁺ and/or H₂ ⁺ ions at apeak depth (D1) and He⁺ ions at a peak depth (D2). The peak depths, (D1)and (D2), are for illustration and are not to be considered to scale.The lengths of the peak depths, (D1) and (D2), are measured from thefront surface 102 of the single crystal silicon donor substrate 100 andalong the central axis 108. The depth of implantation determines thethickness of the single crystal semiconductor device layer in the finalSOI structure.

In some embodiments, the method comprises implanting hydrogen ions(e.g., H₂ ⁺, H⁺ ions, or a combination of H₂ ⁺ and H⁺ ions) through thefront surface of the monocrystalline donor substrate to an average depth(D1) as measured from the front surface toward the central plane. Theaverage depth, (D1), of implanted hydrogen ions may range from about 100Angstroms and about 4000 Angstroms, from about 100 Angstroms and about3000 Angstroms, or between about 500 Angstroms and about 3000 Angstroms,or between about 500 Angstroms and about 2500 Angstroms, as measuredfrom the front surface of the single crystal silicon donor substrate andalong the central axis. In some embodiments, the H₂ ⁺ ion implantationdosage may range from about 4.3×10¹⁵ ions/cm² and about 1.1×10¹⁶ions/cm², or between about 6.8×10¹⁵ ions/cm² and about 1.1×10¹⁶ions/cm², at an implant energy between about 10 Kev and about 40 Kev,such as between about 20 Kev and about 40 Kev, or between about 25 Kevand about 35 Kev, such as about 16 Kev or about 32 Kev. In someembodiments, the H₂ ⁺ ion implantation dosage may range from about4.3×10¹⁵ ions/cm² and about 1.1×10¹⁶ ions/cm², or between about 6×10¹⁵ions/cm² and about 1.1×10¹⁶ ions/cm², at an implant energy between about20 Kev and about 40 Kev, or between about 25 Kev and about 35 Kev, suchas about 16 Kev or about 32 Kev. In some embodiments, the H₂ ⁺ ionimplantation dosage may range from about 5.9×10¹⁵ ions/cm² and about6.7×10¹⁵ ions/cm² at an implant energy between about 10 Kev and about 30Kev, such as between about 15 Kev and about 20 Kev, such as about 16Kev. In some embodiments, the H⁺ ion implantation dosage may range fromabout 5×10¹⁵ ions/cm² and about 2×10¹⁶ ions/cm² at an implant energybetween about 5 Kev and about 20 Kev, such as between about 10 Kev andabout 20 Kev, such as about 16 Kev. In some embodiments, the H⁺ ionimplantation dosage may range from about 1.1×10¹⁶ ions/cm² and about2×10¹⁶ ions/cm² at an implant energy between about 5 Kev and about 20Kev, such as between about 10 Kev and about 20 Kev, such as about 16Kev. In some embodiments, the H⁺ ion implantation dosage may range fromabout 6.1×10¹⁵ ions/cm² and about 6.8×10¹⁵ ions/cm² at an implant energybetween about 5 Kev and about 20 Kev, such as between about 10 Kev andabout 20 Kev, such as about 16 Kev. In some embodiments, a combinationof H₂ ⁺ and H⁺ ions are implanted to an average depth (D1) as measuredfrom the front surface toward the central plane within the above stateddosage ranges and energies.

In some embodiments, the method comprises implanting helium ions (e.g.,He⁺ ions) through the front surface of the monocrystalline donorsubstrate to an average depth (D2) as measured from the front surface102 and along the central axis 108. The average depth, (D2), ofimplanted helium ions may range from about 100 Angstroms and about 4000Angstroms, from about 100 Angstroms and about 3000 Angstroms, or betweenabout 500 Angstroms and about 3000 Angstroms, or between about 500Angstroms and about 2500 Angstroms, as measured from the front surfaceof the single crystal silicon donor substrate and along the centralaxis. In some embodiments, the total helium ion implantation dosage mayrange from about 6×10¹⁵ ions/cm² and about 2×10¹⁶ ions/cm², from about6×10¹⁵ ions/cm² and about 1.3×10¹⁶ ions/cm², such from about 6.3×10¹⁵ions/cm² and about 1.1×10¹⁶ ions/cm², from about 6.6×10¹⁵ ions/cm² andabout 8×10¹⁵ ions/cm², at an implant energy between about 5 Kev andabout 30 Kev, such as between about 10 Kev and about 25 Kev, or betweenabout 15 Kev and about 25 Kev, such as about 22 Kev. In someembodiments, the total helium ion implantation dosage may range fromabout 6×10¹⁵ ions/cm² and about 2×10¹⁶ ions/cm², from about 6×10¹⁵ions/cm² and about 1.3×10¹⁶ ions/cm², such from about 6.3×10¹⁵ ions/cm²and about 1.1×10¹⁶ ions/cm², from about 6.6×10¹⁵ ions/cm² and about8×10¹⁵ ions/cm², at an implant energy between about 5 Kev and about 30Kev, such as between about 10 Kev and about 25 Kev, or between about 15Kev and about 25 Kev, such as about 22 Kev. In some embodiments, thetotal helium ion implantation dosage may range from about 6×10¹⁵ions/cm² and about 2×10¹⁶ ions/cm², from about 6×10¹⁵ ions/cm² and about1.3×10¹⁶ ions/cm², such from about 6.3×10¹⁵ ions/cm² and about 1.1×10¹⁶ions/cm², from about 6.6×10¹⁵ ions/cm² and about 8×10¹⁵ ions/cm², orfrom about 6.6×10¹⁵ ions/cm² and about 7×10¹⁵ ions/cm² at an implantenergy between about 5 Kev and about 20 Kev, such as between about 5 Kevand about 15 Kev, such as about 11 Kev.

Preferably, the peak density, (D1), of H₂ ⁺ ions, H⁺ ions, or acombination of H₂ ⁺ ions and H⁺ions and the peak density, (D2), of He⁺ions are within about 1000 angstroms of each other, within about 600angstroms of each other, or within about 500 angstroms of each other,within about 450 angstroms of each other, within about 400 angstroms ofeach other, within about 300 angstroms of each other, or within about200 angstroms of each other.

In some embodiments it may be desirable to subject the single crystalsemiconductor donor wafers, e.g., single crystal silicon donor wafers,to a clean after the implant. In some preferred embodiments, the cleancould include a Piranha clean (mixture of sulfuric acid and hydrogenperoxide) followed by a DI water rinse and SC1 (mixture of water:aqueousammonium hydroxide:aqueous hydrogen peroxide in 5:1:1 ratio) and SC2(mixture of water:aqueous hydrochloric acid:aqueous hydrogen peroxide in6:1:1 ratio) cleans.

III. Anneal

In some embodiments of the present invention, the ion implanted singlecrystal semiconductor donor substrate 100 is annealed at a temperaturesufficient to form a thermally activated damage layer or cleave plane130 in the single crystal semiconductor donor substrate. This annealoccurs before bonding. By utilizing low implantation energies, thedamage layer 130 occurs at a depth that enables transfer of a thinsilicon layer to the handle substrate, such as a thickness between about500 Angstroms and about 2500 Angstroms.

An example of a suitable tool might be a simple Box furnace, such as aBlue M model. In some preferred embodiments, the ion implanted singlecrystal semiconductor donor substrate is annealed at a temperature offrom about 200° C. to about 350° C., from about 225° C. to about 350°C., such as between about 250° C. and about 300° C. Thermal annealingmay occur for a duration of from about 10 hours to about 10 hours, suchas from about 10 minutes to about 2 hours, or between about 10 minutesand about 60 minutes. Thermal annealing within these temperatures rangesis sufficient to form a thermally activated cleave plane 130. After thethermal anneal to activate the cleave plane 130, the single crystalsemiconductor donor substrate surface is preferably cleaned. In somepreferred embodiments, the clean could include a Piranha clean (mixtureof sulfuric acid and hydrogen peroxide) followed by a DI water rinse andSC1 (mixture of water:aqueous ammonium hydroxide:aqueous hydrogenperoxide in 5:1:1 ratio) and SC2 (mixture of water:aqueous hydrochloricacid:aqueous hydrogen peroxide in 6:1:1 ratio) cleans.

IV. Plasma Activation

In some embodiments, the ion-implanted and annealed single crystalsemiconductor donor substrate is subjected to oxygen plasma and/ornitrogen plasma surface activation. In some embodiments, the oxygenplasma surface activation tool is a commercially available tool, such asthose available from EV Group, such as EVG®810LT Low Temp PlasmaActivation System. The ion-implanted and optionally cleaned singlecrystal semiconductor donor wafer is loaded into the chamber. Thechamber is evacuated and backfilled with an oxygen gas source and/or anitrogen gas source in a carrier gas, such as argon, to a pressure lessthan atmospheric to thereby create the plasma. Oxygen and/or water aresuitable source gases for plasma oxide treatment. Ammonia and/ornitrogen and/or nitric oxide (NO) and/or nitrous oxide (N₂O) gas aresuitable source gases for plasma nitride treatment. Oxynitride plasmaactivation may include oxygen and nitrogen gas sources in the ambientatmosphere. The single crystal semiconductor donor wafer is exposed tothis plasma for the desired time, which may range from about 1 second toabout 120 seconds. Oxygen or nitrogen plasma surface oxidation isperformed in order to render the front surface of the single crystalsemiconductor donor substrate hydrophilic and amenable to bonding to ahandle substrate. After plasma activation, the activated surface isrinsed with deionized water. The wafer is then spun dry prior tobonding.

V. Preparation of the Bonded Structure

With reference to FIG. 1E, the oxidation layer 120 on the front surface102 of the single crystal semiconductor donor substrate 100 having thecleave plane or damage layer 130 is next bonded to a major surface of asemiconductor handle substrate 200 by bringing these surfaces intointimate contact. In some embodiments, the semiconductor handlesubstrate 200 comprises a dielectric layer. The dielectric layer maycomprise insulating materials selected from among silicon dioxide,silicon nitride, silicon oxynitride, hafnium oxide, titanium oxide,zirconium oxide, lanthanum oxide, barium oxide, and any combinationthereof. In some embodiments, the dielectric layer comprises one or moreinsulating material selected from the group consisting of silicondioxide, silicon nitride, silicon oxynitride, and any combinationthereof. In some embodiments, the dielectric layer has a thickness of atleast about 1 nanometer thick, or at least about 10 nanometers thick,such as between about 10 nanometers and about 10,000 nanometers, betweenabout 10 nanometers and about 5,000 nanometers, between 50 nanometersand about 500 nanometers, or between about 100 nanometers and about 400nanometers, such as about 50 nanometers, about 75 nanometers, about 85nanometers, about 100 nanometers, about 150 nanometers, about 175nanometers, or about 200 nanometers. The dielectric layer may be betweenabout 100 angstroms and about 1000 angstroms, such as between about 100angstroms and about 700 angstroms, or between about 100 angstroms andabout 500 angstroms, or between about 100 angstroms and about 250angstroms. In some embodiments, the dielectric layer is much thinner,such as between about 5 angstroms and about 25 angstroms, such asbetween about 10 angstroms and about 15 angstroms.

In some embodiments, the dielectric layer may comprise one or moreinsulating layers, e.g., two insulating layers, three insulating layers,or more. Each insulating layer may comprise a material selected from thegroup consisting of silicon dioxide, silicon nitride, andsiliconoxynitride. Each insulating layer may have a thickness of atleast about 1 nanometer thick, or at least about 10 nanometers thick,such as between about 10 nanometers and about 10,000 nanometers, betweenabout 10 nanometers and about 5,000 nanometers, between 50 nanometersand about 500 nanometers, or between about 100 nanometers and about 400nanometers, such as about 50 nanometers, about 75 nanometers, about 85nanometers, about 100 nanometers, about 150 nanometers, about 175nanometers, or about 200 nanometers.

Since the mechanical bond is relatively weak, in some embodiments, thebonded structure may be further annealed to solidify the bond betweenthe single crystal semiconductor donor substrate 100 and the handlesubstrate 200. In some embodiments of the present invention, the bondedstructure is annealed at a temperature sufficient to form a thermallyactivated cleave plane in the single crystal semiconductor donorsubstrate. An example of a suitable tool might be a simple Box furnace,such as a Blue M model. In some preferred embodiments, the bondedstructure is annealed at a temperature of from about 200° C. to about400° C., such as from about 300° C. to about 400° C. Thermal annealingmay occur for a duration of from 10 minutes to about 10 hours, such asfrom about 10 minutes to 60 minutes.

In some embodiments, the anneal may occur at relatively high pressures,such as between about 0.5 MPa and about 200 MPa, such as between about0.5 MPa and about 100 MPa, such as between about 0.5 MPa and about 50MPa, or between about 0.5 MPa and about 10 MPa, or between about 0.5 MPaand about 5 MPa. In conventional bonding methods, the temperature islikely limited by the “autocleave”. This occurs when the pressure of theplatelets at the implant plane exceeds the external isostatic pressure.Accordingly, conventional anneal may be limited to bonding temperaturesbetween about 350° C. and about 400° C. because of autocleave. Afterimplantation and bond, the wafers are weakly held together. But the gapbetween the wafers is sufficient to prevent gas penetration or escape.Weak bonds can be strengthened by heat treatments, but the cavitiesformed during implant are filled with gas. While heating, the gas insidethe cavities pressurizes. It is estimated that the pressure may reach0.2-1 GPa (Cherkashin et al., J. Appl. Phys. 118, 245301 (2015)),depending on the dosage. When the pressure exceeds a critical value, thelayer delaminates. This is referred to as an autocleave or thermalcleave. It prevents higher temperature or longer time in the anneal.According to some embodiments of the present invention, bonding occursat elevated pressures, e.g., between about 0.5 MPa and about 200 MPa,such as between about 0.5 MPa and about 100 MPa, such as between about0.5 MPa and about 50 MPa, or between about 0.5 MPa and about 10 MPa, orbetween about 0.5 MPa and about 5 MPa, which thereby enables bonding atelevated temperatures. In some embodiments, the bonded structure isannealed at a temperature of from about 300° C. to about 700° C., fromabout 400° C. to about 600° C., such as between about 400° C. and about450° C., or even between about 450° C. and about 600° C., or betweenabout 350° C. and about 450° C. Increasing the thermal budget will havea positive effect on the bond strength. Thermal annealing may occur fora duration of from about 0.5 hours to about 10 hour, such as betweenabout 0.5 hours and about 3 hours, preferably a duration of about 2hours. Thermal annealing within these temperatures ranges is sufficientto form a thermally activated cleave plane. In conventional bondinganneals, the edge of both the handle wafer and donor wafer may becomefar apart due to the roll off. In this area, there is no layer transfer.It is called the terrace. Pressurized bonding is expected to reduce thisterrace, extending the SOI layer further out towards the edge. Themechanism is based on trapped pockets of air being compressed and“zippering” outwards. After the thermal anneal to activate the cleaveplane, the bonded structure may be cleaved.

After the thermal anneal, the bond between the single crystalsemiconductor donor substrate 100 and the handle substrate 200 is strongenough to initiate layer transfer via cleaving the bonded structure atthe cleave plane. Cleaving may occur according to techniques known inthe art. In some embodiments, the bonded structure may be placed in aconventional cleave station affixed to stationary suction cups on oneside and affixed by additional suction cups on a hinged arm on the otherside. A crack is initiated near the suction cup attachment and themovable arm pivots about the hinge cleaving the wafer apart. Cleavingremoves a portion of the semiconductor donor wafer, thereby leaving asingle crystal semiconductor device layer 300, preferably a silicondevice layer, on the semiconductor-on-insulator composite structure. SeeFIG. 1F. The method of the present invention enables the transfer of athin layer of silicon from the donor substrate to the handle substrate.Accordingly, in some embodiments, the silicon layer has a thicknessbetween about 500 Angstroms and about 2500 Angstroms.

After cleaving, the cleaved structure may be subjected to a hightemperature anneal in order to further strengthen the bond between thetransferred device layer 300 and the handle substrate. An example of asuitable tool might be a vertical furnace, such as an ASM A400. In somepreferred embodiments, the bonded structure is annealed at a temperatureof from about 1000° C. to about 1200° C., preferably at about 1000° C.Thermal annealing may occur for a duration of from about 0.5 hours toabout 8 hours, preferably a duration of about 2 to 4 hours. Thermalannealing within these temperatures ranges is sufficient to strengthenthe bond between the transferred device layer and the single crystalsemiconductor handle substrate.

After the cleave and high temperature anneal, the bonded structure maybe subjected to a cleaning process designed to remove thin thermal oxideand clean particulates from the surface. In some embodiments, the singlecrystal semiconductor device layer may be brought to the desiredthickness and smoothness by subjecting to a vapor phase HCl etch processin a horizontal flow single wafer epitaxial reactor using H₂ as acarrier gas.

In some embodiments, an epitaxial layer may be deposited on thetransferred single crystal semiconductor device layer 300. A depositedepitaxial layer may comprise substantially the same electricalcharacteristics as the underlying single crystal semiconductor devicelayer 300. Alternatively, the epitaxial layer may comprise differentelectrical characteristics as the underlying single crystalsemiconductor device layer 300. An epitaxial layer may comprise amaterial selected from the group consisting of silicon, silicon carbide,silicon germanium, gallium arsenide, gallium nitride, indium phosphide,indium gallium arsenide, germanium, and combinations thereof. Dependingupon the desired properties of the final integrated circuit device, theepitaxial layer may comprise a dopant selected from among boron (ptype), gallium (p type), aluminum (p type), indium (p type), phosphorus(n type), antimony (n type), and arsenic (n type). The resistivity ofthe epitaxial layer may range from 1 to 50 Ohm-cm, typically, from 5 to25 Ohm-cm. In some embodiments, the epitaxial layer may have a thicknessbetween about 10 nanometers and about 20 micrometers, between about 20nanometers and about 3 micrometers, such as between about 20 nanometersand about 2 micrometers, such as between about 20 nanometers and about1.5 micrometers or between about 1.5 micrometers and about 3micrometers.

The finished SOI wafer may then be subjected to end of line metrologyinspections and cleaned a final time using typical SC1-SC2 process.

The invention may be further illustrated by the following non-limitingExamples.

EXAMPLE 1

Single crystal silicon donor substrates were subjected to ionimplantation. First, the wafers were subjected to He⁺ ion implantationat a dosage of 7×10¹⁵ cm⁻². The implantation energy was 22 Kev.Thereafter, wafers were subjected to H₂ ⁺ ion implantation or H⁺ ionimplantation. The H₂ ⁺ ion implantation energy was 32 Kev. The H⁺ ionimplantation energy was 16 Kev. Dosages varied according to Table 1.

Stopping and range of ions in matter (SRIM) calculations show that thedifference in the peak of H⁺ and He⁺ depth profiles is about 450angstroms. See FIG. 1. The ion implanted donor substrates were bonded tohandle substrates, annealed, and cleaved. Table 1 further provides theresults of cleaving.

TABLE 1 Result of mechanical cleave operation for various H₂ ⁺ and H⁺doses H₂ ⁺ dose H⁺ dose Cleave result 3.1 x10¹⁵ cm⁻² Did not cleave 6.8x10¹⁵ cm−² Did not cleave 3.7 x10¹⁵ cm⁻² Did not cleave 4 x10¹⁵ cm⁻² Didnot cleave 4.3 x10¹⁵ cm⁻² Cleaved 4.6 x10¹⁵ cm⁻² Cleaved 4.9 x10¹⁵ cm⁻²Cleaved 5.2 x10¹⁵ cm⁻² Cleaved 5.5 x10¹⁵ cm⁻² Cleaved 5.8 x10¹⁵ cm⁻²Cleaved 1.22 x10¹⁶ cm⁻² Cleaved 7.6 x10¹⁵ cm⁻² Cleaved 7.9 x10¹⁵ cm⁻²Cleaved 8.2 x10¹⁵ cm⁻² Cleaved 8.5 x10¹⁵ cm⁻² Cleaved 8.8 x10¹⁵ cm⁻²Cleaved 9.1 x10¹⁵ cm⁻² Cleaved 9.4 x10⁵ cm⁻² Cleaved 9.7 x10¹⁵ cm⁻²Cleaved 2 x10¹⁶ cm⁻² Cleaved 1.03 x10¹⁶ cm⁻² Cleaved

According to the results shown in Table 1, cleaving was not observed atH₂ ⁺ ion implantation dosages of less than 4.3×10¹⁵ cm⁻² or at H⁺ ionimplantation dosages of less than 6.8×10¹⁵ cm⁻² in the event the He⁺ ionimplantation dosage is fixed at 7×10¹⁵ cm⁻² at 22 Kev.

Post cleave, the thickness variation ranges of the transferred silicondevice layers were measured as a function of H₂ ⁺ ion implantationdosage. See FIG. 3, depicting post cleave thickness variation ranges (●)of the transferred silicon device layer for various H₂ ⁺ doses. The datashown in FIGS. 2 and 3 enable determination that the minimal variationin the thickness of transferred silicon device layer is obtained whenthe H₂ ⁺ ion implantation dosage is at least 6×10¹⁵ cm⁻² in combinationwith a fixed He⁺ ion implantation dosage of 7×10¹⁵ cm⁻² at 22 Kevenergy. Notably, the H₂ ⁺ ion implantation dosage to minimize thicknessvariation of the transferred silicon device layer is significantlylarger than that required to obtain cleave through mechanical cleaveoperation.

EXAMPLE 2

Single crystal silicon donor substrates were subjected to ionimplantation. Each wafer was subjected to ion implantation with He⁺ ionand one of H₂ ⁺ or H⁺. The implant dosages for each of He₊, H₂ ⁺ and H⁺were varied. The He⁺ ion implantation dosage was varied between 6.6×10¹⁵cm⁻² to 7×10¹⁵ cm⁻². The implantation energy of He⁺ ion dosing was 11Kev. The H₂ ⁺ ion implantation energy was 16 Kev, and the H⁺ ionimplantation energy was 8 Kev. SRIM calculations show that thedifference in the peak of H⁺ and He⁺ depth profiles is about 200angstroms. See FIG. 4.

The ion implanted donor substrates were bonded to handle substrates,annealed, and cleaved. Table 1 further provides the results of cleaving.

TABLE 2 Result of mechanical cleave operation for various H₂ ⁺ and H⁺doses He⁺ dose H₂ ⁺ dose H⁺ dose Cleave result 7 x10¹⁵ cm⁻² 6.7 x10¹⁵cm⁻² Cleave with voids 7 x10¹⁵ cm⁻² 6.8 x10¹⁵ cm⁻² Did not cleave 7x10¹⁵ cm⁻² 6.3 x10¹⁵ cm⁻² Cleave with voids 7 x10¹⁵ cm⁻² 6.1 x10¹⁵ cm⁻²Did not cleave 7 x10¹⁵ cm⁻² 5.9 x10¹⁵ cm⁻² Cleaved 6.9 x10¹⁵ cm⁻² 6.7x10¹⁵ cm⁻² Cleave with voids 6.9 x10¹⁵ cm⁻² 6.5 x10¹⁵ cm⁻² Did notcleave 6.9 x10¹⁵ cm⁻² 6.3 x10¹⁵ cm⁻² Cleave with voids 6.9 x10¹⁵ cm⁻²6.1 x10¹⁵ cm⁻² Did not cleave 6.9 x10¹⁵ cm⁻² 5.9 x10¹⁵ cm⁻² Partialcleave 6.8 x10¹⁵ cm⁻² 6.7 x10¹⁵ cm⁻² Cleaved 6.8 x10¹⁵ cm⁻² 6.5 x10¹⁵cm⁻² Did not cleave 6.8 x10¹⁵ cm⁻² 6.3 x10¹⁵ cm⁻² Cleaved 6.8 x10¹⁵ cm⁻²6.1 x10¹⁵ cm⁻² Did not cleave 6.8 x10¹⁵ cm⁻² 5.9 x10¹⁵ cm⁻² Cleaved 6.7x10¹⁵ cm⁻² 6.7 x10¹⁵ cm⁻² Cleaved 6.7 x10¹⁵ cm⁻² 6.5 x10¹⁵ cm⁻² Did notcleave 6.7 x10¹⁵ cm⁻² 6.3 x10¹⁵ cm⁻² Cleaved 6.7 x10¹⁵ cm⁻² 6.1 x10¹⁵cm⁻² Did not cleave 6.7 x10¹⁵ cm⁻² 5.9 x10¹⁵ cm⁻² Cleaved 6.6 x10¹⁵ cm⁻²6.7 x10¹⁵ cm⁻² Cleaved 6.6 x10¹⁵ cm⁻² 6.5 x10¹⁵ cm⁻² Did not cleave 6.6x10¹⁵ cm⁻² 6.3 x10¹⁵ cm⁻² Cleaved 6.6 x10¹⁵ cm⁻² 6.1 x10¹⁵ cm⁻² Did notcleave 6.6 x10¹⁵ cm⁻² 5.9 x10¹⁵ cm⁻² Cleaved

At very low energies of He⁺, namely 11 Kev, co-implantation of H⁺ as lowas 5.9×10¹⁵ cm⁻² at 8 Kev can give successful mechanical cleave.

Having described the invention in detail, it will be apparent thatmodifications and variations are possible without departing from thescope of the invention defined in the appended claims.

When introducing elements of the present invention or the preferredembodiments(s) thereof, the articles “a”, “an”, “the” and “said” areintended to mean that there are one or more of the elements. The terms“comprising”, “including” and “having” are intended to be inclusive andmean that there may be additional elements other than the listedelements.

In view of the above, it will be seen that the several objects of theinvention are achieved and other advantageous results attained.

As various changes could be made in the above products and methodswithout departing from the scope of the invention, it is intended thatall matter contained in the above description and shown in theaccompanying drawings shall be interpreted as illustrative and not in alimiting sense.

What is claimed is:
 1. A method of transferring a silicon layer from asingle crystal silicon donor substrate to a handle substrate, the methodcomprising: (a) implanting H₂ ⁺ ions, H⁺ ions, or a combination of H₂ ⁺ions and H⁺ ions through a silicon dioxide layer in contact with a frontsurface of the single crystal silicon donor substrate and through thefront surface of the single crystal silicon donor substrate, the singlecrystal silicon donor substrate comprising two major, parallel surfacesone of which is the front surface and one of which is the back surface,a circumferential edge joining the front surface and the back surface, acentral plane between the front surface and the back surface, a centralaxis perpendicular to the front surface, and a bulk region between thefront surface and the back surface, wherein a peak density, (D1), of H₂⁺ ions, H⁺ ions, or a combination of H₂ ⁺ ions and H⁺ ions is betweenabout 100 Angstroms and about 3000 Angstroms as measured from the frontsurface of the single crystal silicon donor substrate and along thecentral axis; (b) implanting He⁺ ions through the silicon dioxide layerin contact with the front surface of a single crystal silicon donorsubstrate and through the front surface of the single crystal silicondonor substrate, wherein a peak density, (D2), of He⁺ ions is betweenabout 100 Angstroms and about 4000 Angstroms as measured from the frontsurface of the single crystal silicon donor substrate and along thecentral axis and further wherein the peak density, (D1), of H₂ ⁺ ions,H⁺ ions, or a combination of H₂ ⁺ ions and H⁺ ions and the peak density,(D2), of He⁺ ions are within about 600 angstroms of each other; (c)annealing the ion implanted single crystal silicon donor substrate at atemperature between about 200° C. and about 350° C. and for a durationsufficient to form a damage layer in the single crystal silicon donorsubstrate; (d) bonding the silicon dioxide layer in contact with thefront surface of the single crystal silicon donor substrate to adielectric layer in contact with the handle substrate to thereby preparethe multilayer substrate; (e) annealing the multilayer substrate at atemperature between about 200° C. and about 400° C. and for a durationsufficient to thermally activate the damage layer; and (f) cleaving theannealed multilayer substrate at the damage layer in the single crystalsilicon donor substrate to thereby transfer the silicon layer having athickness between about 500 Angstroms and about 2500 Angstroms from thesingle crystal silicon donor substrate to the handle substrate.
 2. Themethod of claim 1 wherein step (a) occurs before step (b).
 3. The methodof claim 1 wherein step (b) occurs before step (a).
 4. The method ofclaim 1 wherein steps (a) and (b) occur simultaneously.
 5. The method ofclaim 1 wherein step (a) comprises (i) implanting H₂ ⁺ ions at a dosagebetween about 4.3×10¹⁵ ions/cm² and about 1.1×10¹⁶ ions/cm² at animplant energy between about 10 Kev and about 40 Kev, (ii) implanting H⁺ions at a dosage between about 5×10¹⁵ ions/cm² and about 2×10¹⁶ ions/cm²at an implant energy between about 5 Kev and about 20 Kev, or (iii)implanting H₂ ⁺ ions at a dosage between about 4.3×10¹⁵ ions/cm² andabout 1.1×10¹⁶ ions/cm² at an implant energy between about 10 Kev andabout 40 Kev and implanting H⁺ ions at a dosage between about 5×10¹⁵ions/cm² and about 2×10¹⁶ ions/cm² at an implant energy between about 5Kev and about 20 Kev.
 6. The method of claim 1 wherein step (a)comprises (i) implanting H₂ ⁺ ions at a dosage between about 4.3×10¹⁵ions/cm² and about 1.1×10¹⁶ ions/cm² at an implant energy between about20 Kev and about 40 Kev, (ii) implanting H⁺ ions at a dosage betweenabout 1.1×10¹⁶ ions/cm² and about 2×10¹⁶ ions/cm² at an implant energybetween about 5 Kev and about 20 Kev, or (iii) implanting H₂ ⁺ ions at adosage between about 4.3×10¹⁵ ions/cm² and about 1.1×10¹⁶ ions/cm² at animplant energy between about 20 Kev and about 40 Kev and implanting H⁺ions at a dosage between about 1.1×10¹⁶ ions/cm² and about 2×10¹⁶ions/cm² at an implant energy between about 5 Kev and about 20 Kev. 7.The method of claim 1 wherein step (a) comprises (i) implanting H₂ ⁺ions at a dosage between about 5.9×10¹⁵ ions/cm² and about 6.7×10¹⁵ions/cm² at an implant energy between about 10 Kev and about 30 Kev,(ii) implanting H⁺ ions at a dosage between about 6.1×10¹⁵ ions/cm² andabout 6.8×10¹⁵ ions/cm² at an implant energy between about 5 Kev andabout 20 Kev, or (iii) implanting H₂ ⁺ ions at a dosage between about5.9×10¹⁵ ions/cm² and about 6.7×10¹⁵ ions/cm² at an implant energybetween about 10 Kev and about 30 Kev and implanting H⁺ ions at a dosagebetween about 6.1×10¹⁵ ions/cm² and about 6.8×10¹⁵ ions/cm² at animplant energy between about 5 Kev and about 20 Kev.
 8. The method ofclaim 1 wherein step (b) comprises implanting He⁺ ions at a dosagebetween about 6×10¹⁵ ions/cm² and about 8×10¹⁵ ions/cm² at an implantenergy between about 5 Kev and about 30 Kev.
 9. The method of claim 1wherein step (b) comprises implanting He⁺ ions at a dosage between about6×10¹⁵ ions/cm² and about 8×10¹⁵ ions/cm² at an implant energy betweenabout 10 Kev and about 30 Kev.
 10. The method of claim 1 wherein step(b) comprises implanting He⁺ions at a dosage between about 6.6×10¹⁵ions/cm² and about 7×10¹⁵ ions/cm² at an implant energy between about 5Kev and about 20 Kev.
 11. The method of claim 1 wherein a peak density,(D1), of H₂ ⁺ ions, H⁺ ions, or a combination of H₂ ⁺ ions and H⁺ ionsis between about 500 Angstroms and about 2500 Angstroms, as measuredfrom the front surface of the single crystal silicon donor substrate andalong the central axis.
 12. The method of claim 1 wherein a peakdensity, (D2), of He⁺ ions is between about 500 Angstroms and about 3000Angstroms, as measured from the front surface of the single crystalsilicon donor substrate and along the central axis.
 13. The method ofclaim 1 wherein the peak density, (D1), of H₂ ⁺ ions, H⁺ ions, or acombination of H₂ ⁺ ions and H⁺ ions and the peak density, (D2), of He⁺ions are within about 500 angstroms of each other.
 14. The method ofclaim 1 wherein the peak density, (D1), of H₂ ⁺ ions, H⁺ ions, or acombination of H₂ ⁺ ions and H⁺ ions and the peak density, (D2), of He⁺ions are within about 400 angstroms of each other.
 15. The method ofclaim 1 wherein the peak density, (D1), of H₂ ⁺ ions, H⁺ ions, or acombination of H₂ ⁺ ions and H⁺ ions and the peak density, (D2), of He⁺ions are within about 200 angstroms of each other.
 16. The method ofclaim 1 wherein step (c) comprises annealing the ion implanted singlecrystal silicon donor substrate at a temperature between about 250° C.and about 300° C. for a duration between 10 minutes and 60 minutes. 17.The method of claim 1 wherein step (e) comprises annealing the ionimplanted single crystal silicon donor substrate at a temperaturebetween about 300° C. and about 400° C. for a duration between 10minutes and 60 minutes.
 18. The method of claim 1 wherein the siliconlayer having the thickness between about 500 Angstroms and about 2500Angstroms transferred from the single crystal silicon donor substrate tothe handle substrate has a thickness variation less than about 10angstroms.
 19. A method of transferring a silicon layer from a singlecrystal silicon donor substrate to a handle substrate, the methodcomprising: (a) implanting H₂ ⁺ ions, H⁺ ions, or a combination of H₂ ⁺ions and H⁺ ions through a silicon dioxide layer in contact with a frontsurface of the single crystal silicon donor substrate and through thefront surface of the single crystal silicon donor substrate, the singlecrystal silicon donor substrate comprising two major, parallel surfacesone of which is the front surface and one of which is the back surface,a circumferential edge joining the front surface and the back surface, acentral plane between the front surface and the back surface, a centralaxis perpendicular to the front surface, and a bulk region between thefront surface and the back surface, wherein the H₂ ⁺ ions are implantedat an implant energy between about 10 Kev and about 40 Kev and the H⁺ions are implanted at an implant energy between about 5 Kev and about 20Kev; (b) implanting He⁺ ions through the silicon dioxide layer incontact with the front surface of a single crystal silicon donorsubstrate and through the front surface of the single crystal silicondonor substrate, wherein the He⁺ ions are implanted at an implant energybetween about 5 Kev and about 30 Kev; (c) annealing the ion implantedsingle crystal silicon donor substrate at a temperature between about200° C. and about 350° C. and for a duration sufficient to form a damagelayer in the single crystal silicon donor substrate; (d) bonding thesilicon dioxide layer in contact with the front surface of the singlecrystal silicon donor substrate to a dielectric layer in contact withthe handle substrate to thereby prepare the multilayer substrate; (e)annealing the multilayer substrate at a temperature between about 200°C. and about 400° C. and for a duration sufficient to thermally activatethe damage layer; and (f) cleaving the annealed multilayer substrate atthe damage layer in the single crystal silicon donor substrate tothereby transfer the silicon layer having a thickness between about 500Angstroms and about 2500 Angstroms from the single crystal silicon donorsubstrate to the handle substrate.
 20. The method of claim 19 whereinstep (a) occurs before step (b).
 21. The method of claim 19 wherein step(b) occurs before step (a).
 22. The method of claim 19 wherein steps (a)and (b) occur simultaneously.
 23. The method of claim 19 wherein step(a) comprises (i) implanting H₂ ⁺ ions at a dosage between about4.3×10¹⁵ ions/cm² and about 1.1×10¹⁶ ions/cm² at an implant energybetween about 10 Kev and about 40 Kev, (ii) implanting H⁺ ions at adosage between about 5×10¹⁵ ions/cm² and about 2×10¹⁶ ions/cm² at animplant energy between about 5 Kev and about 20 Kev, or (iii) implantingH₂ ⁺ ions at a dosage between about 4.3×10¹⁵ ions/cm² and about 1.1×10¹⁶ions/cm² at an implant energy between about 10 Kev and about 40 Kev andimplanting H⁺ ions at a dosage between about 5×10¹⁵ ions/cm² and about2×10¹⁶ ions/cm² at an implant energy between about 5 Kev and about 20Kev.
 24. The method of claim 19 wherein step (a) comprises (i)implanting H₂ ⁺ ions at a dosage between about 4.3×10¹⁵ ions/cm² andabout 1.1×10¹⁶ ions/cm² at an implant energy between about 20 Kev andabout 40 Kev, (ii) implanting H⁺ ions at a dosage between about 1.1×10¹⁶ions/cm² and about 2×10¹⁶ ions/cm² at an implant energy between about 5Kev and about 20 Kev, or (iii) implanting H₂ ⁺ ions at a dosage betweenabout 4.3×10¹⁵ ions/cm² and about 1.1×10¹⁶ ions/cm² at an implant energybetween about 20 Kev and about 40 Kev and implanting H⁺ ions at a dosagebetween about 1.1×10¹⁶ ions/cm² and about 2×10¹⁶ ions/cm² at an implantenergy between about 5 Kev and about 20 Kev.
 25. The method of claim 19wherein step (a) comprises (i) implanting H₂ ⁺ ions at a dosage betweenabout 5.9×10¹⁵ ions/cm² and about 6.7×10¹⁵ ions/cm² at an implant energybetween about 10 Kev and about 30 Kev, (ii) implanting H⁺ ions at adosage between about 6.1×10¹⁵ ions/cm² and about 6.8×10¹⁵ ions/cm² at animplant energy between about 5 Kev and about 20 Kev, or (iii) implantingH₂ ⁺ ions at a dosage between about 5.9×10¹⁵ ions/cm² and about 6.7×10¹⁵ions/cm² at an implant energy between about 10 Kev and about 30 Kev andimplanting H⁺ ions at a dosage between about 6.1×10¹⁵ ions/cm² and about6.8×10¹⁵ ions/cm² at an implant energy between about 5 Kev and about 20Kev.
 26. The method of claim 19 wherein step (b) comprises implantingHe⁺ ions at a dosage between about 6×10¹⁵ ions/cm² and about 8×10¹⁵ions/cm² at an implant energy between about 5 Kev and about 30 Kev. 27.The method of claim 19 wherein step (b) comprises implanting He⁺ ions ata dosage between about 6×10¹⁵ ions/cm² and about 8×10¹⁵ ions/cm² at animplant energy between about 10 Kev and about 30 Kev.
 28. The method ofclaim 19 wherein step (b) comprises implanting He⁺ ions at a dosagebetween about 6.6×10¹⁵ ions/cm² and about 7×10¹⁵ ions/cm² at an implantenergy between about 5 Kev and about 20 Kev.
 29. The method of claim 19wherein a peak density, (D1), of H₂ ⁺ ions, H⁺ ions, or a combination ofH₂ ⁺ ions and H⁺ ions is between about 500 Angstroms and about 2500Angstroms, as measured from the front surface of the single crystalsilicon donor substrate and along the central axis.
 30. The method ofclaim 19 wherein a peak density, (D2), of He⁺ ions is between about 500Angstroms and about 3000 Angstroms, as measured from the front surfaceof the single crystal silicon donor substrate and along the centralaxis.
 31. The method of claim 19 wherein the peak density, (D1), of H₂ ⁺ions, H⁺ ions, or a combination of H₂ ⁺ ions and H⁺ ions and the peakdensity, (D2), of He⁺ ions are within about 500 angstroms of each other.32. The method of claim 19 wherein the peak density, (D1), of H₂ ⁺ ions,H⁺ ions, or a combination of H₂ ⁺ ions and H⁺ ions and the peak density,(D2), of He⁺ ions are within about 400 angstroms of each other.
 33. Themethod of claim 19 wherein the peak density, (D1), of H₂ ⁺ ions, H⁺ions, or a combination of H₂ ⁺ ions and H⁺ ions and the peak density,(D2), of He⁺ ions are within about 200 angstroms of each other.
 34. Themethod of claim 19 wherein step (c) comprises annealing the ionimplanted single crystal silicon donor substrate at a temperaturebetween about 250° C. and about 300° C. for a duration between 10minutes and 60 minutes.
 35. The method of claim 19 wherein step (e)comprises annealing the ion implanted single crystal silicon donorsubstrate at a temperature between about 300° C. and about 400° C. for aduration between 10 minutes and 60 minutes.
 36. The method of claim 19wherein the silicon layer having the thickness between about 500Angstroms and about 2500 Angstroms transferred from the single crystalsilicon donor substrate to the handle substrate has a thicknessvariation less than about 10 angstroms.